A252178 Number of length 2+2 0..n arrays with the sum of the maximum minus the minimum of adjacent triples multiplied by some arrangement of +-1 equal to zero.

12, 49, 132, 285, 536, 917, 1464, 2217, 3220, 4521, 6172, 8229, 10752, 13805, 17456, 21777, 26844, 32737, 39540, 47341, 56232, 66309, 77672, 90425, 104676, 120537, 138124, 157557, 178960, 202461, 228192, 256289, 286892, 320145, 356196, 395197

Offset: 1

Author

R. H. Hardin, Dec 15 2014

Keywords

• nonn

Examples

			Some solutions for n=6:
..4....2....0....4....2....6....2....1....4....1....4....4....2....4....2....2
..6....2....2....5....2....6....2....1....3....1....5....1....6....3....4....0
..0....0....3....1....1....0....4....6....2....2....0....6....0....4....2....6
..5....2....0....2....1....5....4....5....1....2....2....5....3....4....3....0
		

Links

• R. H. Hardin, Table of n, a(n) for n = 1..210

Crossrefs

Row 2 of A252177.

Formula

Empirical: a(n) = (1/6)*n^4 + (7/3)*n^3 + (29/6)*n^2 + (11/3)*n + 1.

Conjectures from Colin Barker, Dec 01 2018: (Start)

G.f.: x*(12 - 11*x + 7*x^2 - 5*x^3 + x^4) / (1 - x)^5.

a(n) = 5*a(n-1) - 10*a(n-2) + 10*a(n-3) - 5*a(n-4) + a(n-5) for n>5.

(End)